Introduction Roll grinding machines are an indispensable piece of equipment in the equipment manufacturing industry. They are mainly used for grinding various rolls with moderate convexity or concavity. The convexity or concavity of the rolls is designed to eliminate deformation and thermal expansion caused by the force exerted by the workpiece on the rolls during rolling, ensuring equal clearance between the rolls and uniform thickness of the workpiece along its width. Roll grinding machines share characteristics with cylindrical grinding machines, but they also have a height-reduction mechanism. The contour curve on the roll is achieved through this mechanism. Besides grinding flat rolls, they are also required to grind rolls with moderate convexity or concavity. Therefore, the motion of roll grinding machines is relatively complex. In addition to the rotary motion of the grinding wheel and the workpiece, they also need to perform longitudinal relative motion while simultaneously undergoing a certain radial relative motion. Consequently, the mechanical structure and transmission principle of this type of grinding machine are quite complex. In recent years, due to the rapid development of the metallurgical, papermaking, rubber, plastics, and printing and dyeing industries, the technical requirements for roll grinding have been increasing. To adapt to user needs and market changes, the development of CNC roll grinding machines has become necessary. On the other hand, with the development of computer technology, microelectronics technology, and CNC technology, PC-based open CNC systems have become an important direction in the current development of CNC technology. Combining the characteristics of roll grinding machines and the current development trend of open CNC systems, developing a roll grinding machine CNC system based on an industrial PC and a PMAC motion control card has become crucial in the development of CNC roll grinding machines. CNC System Hardware Composition Based on the characteristics of roll grinding machines and user needs, the designed roll grinding machine is mainly used for grinding cylindrical and conical roll surfaces, sinusoidal curve roll surfaces with moderate convexity or concavity, and special curve roll surfaces. During the grinding process, the measuring device can measure the roll shape of the workpiece and automatically enter compensation grinding based on the measurement results until the required accuracy is achieved. Based on the preceding analysis, the CNC system of this roll grinding machine must be able to control motion in the following directions: the reciprocating motion of the z-axis for longitudinal feed of the grinding wheel, the radial feed of the grinding wheel, the F-axis rotation of the eccentric sleeve in the intermediate and high mechanisms, the motion of the measuring device's axis, and the rotation of the workpiece and the grinding wheel. The specific definitions of the motion directions of each axis on the roll grinding machine are shown in Figure 1. Based on the above considerations and the characteristics of an open CNC system, the designed CNC system for the roll grinding machine consists of the following components: one PC, one PMAC motion control card and its accessories, five sets of AC servo drives and servo motors, two sets of DC speed controllers and DC speed-regulating motors, one long and one short optical grating for measurement, two probes, and two encoders. The hardware composition of the CNC system is shown in Figure 2. This CNC system uses a PCUltralite multi-axis motion control card from Delta Tau Systems, USA. It has multiple functions and can achieve high-precision contour control, making it a key component of this system. The main functions of P MAC include: linear and circular interpolation, CNC code processing, tool diameter and lead screw compensation, cubic spline trajectory calculation, and "S-curve" acceleration and deceleration to ensure smooth motion during acceleration and deceleration. The card communicates with the host computer in two ways: serial RS and bus. The system designed in this paper uses a P MAC card inserted into the ISA slot of the industrial computer, employing a bus method for communication between the industrial computer and the card. In the CNC system of the roll grinding machine, the actuators are AC servo drives and their AC servo motors, totaling five sets: one each for the z-axis, f-axis, s-axis, and s-axis. The f-axis is used for radial feed of the grinding wheel; the f-axis is used for the system's high-speed mechanism to grind convex or concave rolls and rolls with special curved profiles; the z-axis is used for the axial reciprocating motion of the grinding wheel; and the f-axis motors are used to drive the grating head to measure the diameter, roll shape, roundness, and coaxiality of the processed rolls. A DC speed control device and a DC motor drive the grinding wheel and workpiece to rotate and adjust their speed to complete the grinding process of the rolls. Encoders at the ends of the X, Z, and F axes form a semi-closed-loop servo system to improve the machining accuracy of the CNC system. The PC handles non-real-time control tasks such as file management, curve node calculation, grinding process programming, and parameter setting for the CNC system. CNC System Software Structure PC-based open CNC systems offer great flexibility, fully utilizing the rich hardware and software resources and powerful technical advantages of the PC. This system is an open CNC system based on a PC and a P MAC motion control card. The PC handles non-real-time system management, parameter setting user interface, graphical display, and online fault diagnosis, while the real-time control is handled by the P MAC motion control card based on a high-performance DSP chip. The system software consists of four parts: the CNC system host computer application, the communication driver between the host and host computers, the motion program, and the PLC program in the P MAC card that monitors various input and output quantities. The machine establishes communication with the PMAC card through the Pmac.dll dynamic link library included with the PMAC card. The host computer application is developed using Delphi 7. The motion program and PLC program are written and debugged using the software included with the PMAC card, and then downloaded to the PMAC card for execution through functions in the dynamic link library. The host computer application mainly displays the CNC system's operating interface on the screen, providing an intuitive operating environment for the operator of the CNC roll grinding machine. Based on the analysis of the hardware structure and user requirements of the roll grinding machine's CNC system, the module structure of the host computer application is shown in the figure. The functions of each module are as follows: System initialization: Powering on the system, performing corresponding sequential electrical actions, and establishing normal communication between the host and the PMAC card. Machining parameter setting: Curve programming (parameterizing specific curves), setting basic system parameters, grinding process programming, and setting other system parameters. Machining process: Selecting the grinding curve and grinding process, real-time display of machining parameters, monitoring of each axis during manual grinding, and process optimization during grinding. Measurement Selection: Measure the diameter, roll shape, roundness, and coaxiality of the workpiece. Measurement Curve Reproduction: Display the theoretical grinding curve, measurement curve, and error curve; measurement and error analysis; printing. Grinding Wheel Compensation and Dressing: Set grinding wheel compensation parameters, control grinding wheel dressing, and set and calculate the grinding wheel correction curve. Diagnosis: Diagnose each I/O and internal relay of the PLC for maintenance and debugging. System Help: Instructions for system operation. In the design of the host computer application, considering user convenience and the characteristics of CNC software, the menu uses shortcut keys, consisting of F1 and function keys. Each menu and button has corresponding Chinese prompts. When the operator presses a shortcut key, they enter the corresponding submenu interface. The main interface of the CNC software is shown in Figure 4. Implementation of Some Functions of the CNC Software. 1 System Initialization. CNC software differs from general application software; it is a real-time multi-task control system with high requirements for safety and real-time performance. To ensure the system meets the needs of real-time machining and the control of the roll grinding machine, system initialization is essential before running the CNC software. The first step in system initialization is establishing normal communication between the PC and the PMAC card, which is accomplished by calling functions from the dynamic link library using Delphi. When exiting the system, the card must be closed using the function `ClosePmacdevice(dwDevice)`. This paper places the system's basic parameters in a `Basic.CNC` file. These parameters include: setting the working status of relevant interfaces; setting constants or clearing certain registers or memory; returning each machine axis to its corresponding position; defining M variables used in the program; setting motor parameters; and setting I variables for the PMAC card. After successful communication between the PC and the PMAC, the `PmacDownloadFile` function from the `Pmac.dll` dynamic link library is used to download the `.CNC` file to the PMAC card, completing the system initialization process. 2. Special Curve Programming: This module primarily handles the input, storage, modification, printing, and editing of special curve node coordinates, preparing for subsequent theoretical curve display and contour processing. First, a database sk-data.mdb was designed using Microsoft Access 2000. Leveraging Delphi's powerful database capabilities, the input node data is stored in a pre-designed database table, providing users with a convenient and efficient parameter editing environment. This system can program 1-5 special curves. In the curve programming interface, first, the special curve number is entered, followed by the length of the curve to be edited. Then, 500 equidistant division points are displayed on the screen. The target value for each point is then entered, and clicking "Save" completes the programming of one special curve. The special curve programming interface is shown in Figure 5. On this interface, the nodes of the special curve being edited can be modified, and stored curves can be edited and printed. Conclusion This paper takes the roll grinding machine as the controlled object and constructs an open CNC system based on a PC and with a PMAC card as the core. The hardware structure and software system are studied. Based on a full understanding of the process characteristics of the roll grinding machine, combined with the characteristics of the CNC roll grinding machine and user needs, a special CNC software for the roll grinding machine is designed and developed using the high-level programming language Delphi 7.0 with a modular structure and object-oriented programming ideas. The functions of some modules are implemented. Practice shows that this open system can shorten the development cycle and ensure the high stability of the system's machining accuracy. The modular structure in the design of the CNC software greatly enhances the system's versatility and portability, and is also conducive to the future expansion of the system's functions. References Tang Shuiyuan, Lu Jiping. CNC transformation of roll grinding machine [J]. Computer-aided design and manufacturing, 2000 (5): 81-82. Chen Yuan, Research and development of open CNC system for roll grinding machine based on PMAC. Xi'an: Xi'an University of Science and Technology. 2004. 'S Manuals .DEL TAT AU DA TAS YS TE MS, I NC,.『 4]P MAC P co mm S oftware Manua 1.DE LTAT AU DA TAS YS .。 I NC。 1999. Yin Jiafan, Wang Sunan. Research on PC-based open numerical control system [J]. Machine Tool & Hydraulics, 2003 (2): 90. Ju Hua. Wang Wen, et al. Open numerical control online non-contact measurement system with integrated control of IPC and P MAC [J]. Combined Machine Tool & Automated Machining Technology, : 46-48.. W.Ma, YC chen, XHZ hang. etc. P MAC ·, Jinan, China, 2004, : 18-19. Lai Guoting, et al. Research on open CNC system based on P MAC [J]. Manufacturing Automation, 2002, 24(9): 34-36. Dai Xiaohua, Wang Wen, et al. Review of open CNC system research [J]. Modular Machine Tool & Automated Machining Technology, 2000(11): 5-7. Click here to download materials: Development of CNC system for roll grinding machine based on P MAC and PC. Editor: He Shiping